Remote control systems are used to allow a controlled device to be controlled from a remote location. For example, many consumer electronic products such a television receivers, video cassette recorders (VCRs), audio record and cassette players, have associated hand-held remote control transmitter units for controlling various functions from a viewing or listening position.
A typical remote control transmitter unit has a keyboard with a plurality of keys or buttons corresponding to the functions to be controlled. Usually the more functions that have to be controlled, the greater the number of keys that have to be provided. Since modern consumer electronic products have a very large number of control functions, the keyboard of remote control transmitter units of such products are often cluttered with keys. Some manufacturers provide a single, unified remote control unit for several controlled devices, such as a television receiver and a VCR which are intended to be operated together. The keyboards of such unified remote control transmitter units, therefore, may contain even more keys than dedicated remote control units for individual controlled devices.
Remote control transmitter units with a large number of keys tend to be cumbersome to use and expensive to manufacture. Accordingly, there is a desire in the art to reduce the number of keys of remote control transmitter units.
There have been attempts to reduce the number of keys by assigning multiple functions to at least some keys. The particular function of a key at any time can be determined by a mode switch or by the sequence of prior key operations. To guide users, labels on the keyboard identifying the various functions of the keys may be employed. It is also possible in a television system with a viewing screen, to use the viewing screen to display information indicating the functions of the keys of the remote control transmitter during various modes of operation. However, such prior approaches are indirect and, therefore, may be confusing.
To avoid the confusion that may result from the indirect key function identification technique described above, it has been proposed in European Patent Application Publication No. 0 120 345 to provide a display arrangement on the remote control transmitter unit itself to identify the particular functions of keys at various steps of a control operation. The display arrangement may take the form of individual display devices located near respective keys or of individual display elements underlying transparent keys. Each display device is capable of displaying characters designating the function of the associated key. The information for the key function display arrangement is stored in a display memory contained in the remote control transmitter unit. For expansion, display memories for additional devices that may be controlled by the remote control transmitter unit may be added to the remote control transmitter unit.
While the type of remote control system described in the European patent application is useful, the provisions for expanding its capability to control new devices by adding display memories may be troublesome to users and may limit the number of devices that can be controlled due to wiring and size constraints of the remote control transmitter unit.